Isaac e



ISAAOIEJGRAIG, OFoAMDE'N, OHIO.

I Letters Potent No. 74,314, dated February 11, 1868 dntedatcd January 30, 1868.

I IMPROVEMENT IN THE MANUFACTURE OF SHEET-IRON.

the Stlgsbtlt ttfttx'tir it iu the: girders Eiatent ant making put at tig t time.

TO ALL WHOM IT MAY CONCERN: r g

Be it known that I, ISAAC E. CRAIG, of Camden, in the county of Preble, nndSteteof Ohio, have discorered a new and improved Method of Mcnufacturing Sheet Iron; and do hereby declare the following is a. full and exact description thereof.

The, nature of my discovery consists in so softening the iron to bc-rolled into sheetsfby nlloyingtin therewith, that after it is rolled into sheets it does not need to pass through an annealingprocess, to giveit' the required softness and flexibilityfor use in the arts.

To enable others skilled in the art to make use of my mvention, I will proceed to describe the method of operating the same. p g

i The iron used maybe of any of the different kinds of pig which are known asfmill-ironf or used in mills for the purpose of making refined iron. The tin is the ordinary hnr'or block-tin bf-commercel The tin may be alloyed with the pig-metal at any time when it is inn molten state, but the inventor believes the best method is to introduce the tin into the molten iron in a bloomery or knobbling fire, whenit is almost readyto stiffen up Land be Worked intothe loup. No great importance attaches, however, to the'exsct time of introducing the tin, as the alloy, when once formed, is not liobleto separate. lhe tin should'be out up into small pieces before being cast into the molten metal, and distributed as equally as possible through the metal, and afterward carefully stirred. In the boiling or rcrerberctory furnace, the alloying of the metals may be efiected in thesnme way, but the quality of the manufactured iron will be as much inferior to thot mode in the bloomery as ordinary boiled iron is to charcoal-iron; or theolloy may be made in a) large crucible, containing steel inn molten state,

as in thecruciblosfor the manufacture of Bessemer steel, after the steel is produced, and while still melted. In" this case, however, car'c should be-had to cover the surface of the steel with powdered charcoal, to prevent the loss of tin by oxidation 'before the metals are alloyed. p

When the metals are reddy for rolling, the process of looping or balling up not'difi'ering from the common one, they are rolled in the ordinary manner, and polished, by the process understood, byrollers'; polishing being an efi'eet of friction, from passing the sheets, in packs, at a. low'heut, between either soft or chilled sheet rolls, when, after shooting, they are-ready for the bundl-er. F

The proportion of tin necessary to be used varies with difi'erent grades of pig-metal; being, as a. general rule, from five to ten per cent. of'the quantity 'of iron, five per cent. being enough for good soft iron, a larger proportion being required for interior grades. As a. trial proportion, the discoverer reeommends seven or eight per cent. of tin. It, with this proportion, the produced sheets should be softer than needed, a. less percentage of tin may afterward be used; if not soft enough, n'larger proportion of tin is needed; the softness, without annealing, as in the enclosed sample, affording the manufacturer a. ready means of determining, after a few trials,

the proper proportion for any grade of pig-metal, it being possible that the proportion of tin may sometimes pass out of the above-mentioned limits.

What I'claim as my invention, and desire to'seeure by Letters Patent, is Softening of iron intended to be rolled into sheets, by the alloying of tin therewith.

' IsfAAo E. CRAIG.

Witnesses:

J. SHEAFER, E. G. SHEAFER. 

